GP3 points leader Luca Ghiotto took a third victory of the season at Spa to extend his championship advantage over second-place man Ocon.
The race started in chaotic fashion as reverse grid polesitter Aleksander Bosak made a dismal getaway, allowing fellow front row starter Alex Palou into the lead at La Source ahead of ART trio Alfonso Celis Jr, Ocon and Marvin Kirchhofer.
But worse was to come for Bosak, who suffered a front-right puncture exiting Blanchimont on the second lap and speared into the barriers as a result, the rear of his Arden machine completely destroyed in the impact.
One of the Pole's detached wheels then made its way back on to the circuit, hitting Matt Parry's car and causing the Brit to have his own crash.
The carnage necessitated the Safety Car, by which time Ocon had passed Celis for second and Ghiotto had moved ahead of Kirchhofer for fourth. When the race got back under way, Ghiotto got the better of Celis exiting La Source to take third.
A second caution period was caused when Antonio Fuoco tried to go round the outside of Kirchhofer for fifth at Les Combes, the two colliding and retiring as a result - though not before Fuoco's car drifted back into the path of the pack, where it was lucky to only be clipped lightly by Artur Janosz.
After the subsequent restart, Ghiotto made short work of Ocon, slipping past his chief title rival along the Kemmel Straight, before repeating the move on Palou on the very next lap to take the lead.
Ocon followed Ghiotto through to move into second, but despite making up ground in the closing stages was unable to get close enough to threaten the Italian.
Celis was able to pass Palou, suffering with a higher downforce setup, to take his maiden GP3 podium finish, with Matheo Tuscher - up from 20th on the grid - doing likewise to take a creditable fourth.
Palou had to be content with fifth, ahead of Alex Fontana, Janosz and Ralph Boschung.
Emil Bernstorff, who inherited his first win of the season after Ocon's post-race penalty on Saturday, was an early casualty as he was hit from behind at the first corner, causing him to make contact with Janosz's car, deranging his front-left suspension.
|2||Esteban Ocon||ART Grand Prix||0.878|
|3||Alfonso Celis||ART Grand Prix||5.144|
|4||Matheo Tuscher||Jenzer Motorsport||6.891|
|5||Alex Palou||Campos Racing||7.993|
|6||Alex Fontana||Status Grand Prix||8.348|
|8||Ralph Boschung||Jenzer Motorsport||11.014|
|9||Adderly Fong||Koiranen GP||11.611|
|10||Pal Varhaug||Jenzer Motorsport||12.230|
|13||Kevin Ceccon||Arden International||14.506|
|14||Seb Morris||Status Grand Prix||14.900|
|16||Jimmy Eriksson||Koiranen GP||16.008|
|17||Sandy Stuvik||Status Grand Prix||18.795|
|18||Zaid Ashkanani||Campos Racing||32.579|
|Ret||Marvin Kirchhofer||ART Grand Prix|
|Ret||Alex Bosak||Arden International|
|Ret||Matt Parry||Koiranen GP|
|Ret||Emil Bernstorff||Arden International|